Within the field of wireless telecommunications systems there exists a system referred to as the personal handy phone system, otherwise known as PHS. Within the personal handy phone system a user of a portable or personal station (PS) is able to communicate with a user of another telecommunication device by way of a cell station (CS). A portable station and a cell station of the personal handy phone system communicate by way of a wireless digital radio interface that utilizes communication frames and slots.
When a portable station receives transmitted data from a cell station, the data contained within the preamble field of the received communication slot is used by the portable station hardware for clock recovery from the data stream. Once the portable station is synchronized with the cell station, the data contained within the preamble field is generally not needed during the remainder of the communication session between the portable station and the cell station. The personal handy phone system standard does not define the format or usage of the preamble field once it has been utilized for its intended purpose by the portable station and the cell station. Instead, the data within the neglected preamble field is left to the user to define. Within the prior art, the neglected preamble field has been used to contain extended common access channel field information.
By containing extended common access channel field data within the neglected preamble field, the bandwidth of the common access channel field is increased for some channels, e.g., the user specific control channel (USCCH) and the user specific packet channel (USPCH). Moreover, some network service providers use the common access channel (CAC) field and the extended common access channel field data contained within the neglected preamble field for specific services. If the preamble field is utilized for containing extended common access channel data, it is important to determine whether the extended common access channel data within that field is free of errors once it is received by a portable station.
The prior art procedure to determine if the extended common access channel data within the preamble field is free of errors after reception involves storing it within the portable station memory and performing a cyclic redundancy check (CRC) on it. Unfortunately, there is a problem associated with this prior art procedure. Today, the personal handy phone system does not differentiate preamble data from extended common access channel data until much of the data is received. As a result of not being able to identify the data, the prior art procedure processes (e.g., data storage and perform cyclic redundancy check) any data contained within the preamble field. The problem associated with the prior art procedure is that processing preamble data is useless in most cases, resulting in needless consumption of portable station power. Optimizing power consumption within a portable station is very critical because it operates under the limited power of an internal battery.
Therefore, it would be advantageous to provide a method and system that enables a portable station within the personal handy phone system to utilize the preamble field of the communication interface to contain extended common access channel field information while optimizing power consumption. The present invention provides this advantage.